It is known that a telecommunication network is operated by interconnected switches. An example of such a network is the Public Switched Telecommunications Network (PSTN). This network may be combined with a radio telecommunications network for mobile communication.
The switches route calls from one subscriber to another, by passing control data and voice data along circuits, which are the interconnecting links among the switches in the network.
A subscriber may be connected to the network via a network access point using a peripheral apparatus, such as a telephone, a modem, an answering device, IVR equipment, conference call hardware or any apparatus used for communication via or interfacing with the network. Likewise, a voice service such as teleconferencing, news, weather forecast, traffic announcements or any other service may be connected to the network via a network access point also using a peripheral apparatus. A peripheral apparatus may originate connections or calls or receive them and has control circuitry to control these calls.
Similarly, each switch has its own control circuitry for connecting a call to another switch. The control circuitry implements rules telling the switch what to do with an incoming call. A call is originated by communicating a control signal from a peripheral apparatus to a switch and a peripheral apparatus receives a call by receiving control signals from a switch. Upon acceptance of the control signals, a voice connection is established between the switch and the peripheral apparatus via a voice-only circuit.
Once a call is received by one switch, whereby the call is accompanied with control data, the switch will on the basis of that control data route the call to a next switch or to another peripheral apparatus or service, whereby voice-only circuits are used to carry the voice data.
The path through the network from a peripheral apparatus to a particular switch may be referred to as one leg of a call or a half call. The path from that switch to another peripheral apparatus may be referred to as the other leg of the call or other half call.
In some cases, simple routing or switching is not enough. It may be desirable that a call is connected to a service, e.g., an information service. In other cases, more complex switching is required, e.g., in the case of call forwarding where a subscriber has moved to another number.
“IN” (Intelligent Networking) was introduced to perform such services. Switches connected to IN systems detect calls which require special treatment. The control signals of such calls are diverted to the IN system where decisions are made on the further treatment of the call. The result of these decisions is communicated to the switch, which will treat each such call accordingly.
Nowadays, there is a need for call control from a different perspective. With the emerging of computer networks, Internet, LANs and WANs, a need arises to be able to control telecom connections from the computer environments. IN provides for such possibilities. It is now possible to initiate a call or service from a computer network which is connected to an IN system, which is, in turn, connected to a switch and thereby able to establish calls, whereby the two legs of the call have their starting point at the switch connected or controlled by the IN system.
IN systems however are expensive and are limited in their functionality. They are bound by telecom standards, which evolve slower than the information technology now available.
The U.S. Pat. No. 6,337,858 discloses a further development, whereby a switch fabric is used outside of the telecom network. This switching fabric, comprising switch and switch control means is connected to and controlled by computer telephony hardware. This architecture is referred to as computer telephony integration (CTI) hardware. In this architecture, it is possible to set up a first call from the switching fabric to a first peripheral apparatus and a second call from the switching fabric to a second peripheral apparatus. Both calls constitute a leg to the respective peripheral apparatuses. After the legs have been set up, the CTI than bridges the calls.
This architecture gives control over both legs of the call. The result is great flexibility of building calls from the CTI environment. The CTI may be part of the Internet, a LAN or a WAN. Thereby, all kinds of users may be enabled to create telecom services in relation to, for example, a Web based service.
Despite the advantages of the solution disclosed in U.S. Pat. No. 6,337,858, a switch fabric outside of the telecommunication network is required. Switches are expensive equipment.